Procedures for the separation and concentration of microgram to nanogram amounts of thallium from gram amounts to galena and meteorite metal, sulfide, and silicate phases were developed and are described. The thallium is extracted from aqueous bromide of chloride solutions of moderate acidity using diethyl ether. A device for elimination of the large volumes of solvent by dropwise evaporation is described. Organic matter in the residue is destroyed by treatment with aqua regia, and the thallium is the residue is converted to the nitrate for spectrochemical or mass-spectrometric examination. The presence of thallium in the residue is tested by Rhodamine B. test.

The differential cross-section for bremestrahlung in p-p collisions at an energy of 140 Mev is calculated at the upper end of the photon spectrum. the only transition which is considered is the E2 transition between 1D2 and the 1S0 state. The Siegart theorem is used and influence of the Coulomb force between the two protons is neglected.

A geometrical treatment has been used to outline the theoretical properties of optical fibers which are imperfect as well as geometrically and optically perfect. Experiments have been performed to measure some to the optical properties of individual fibers and fiber bundles.

The objective of the study which is being carried out under contract AT(30-1)-2477 is the exploration of all aspects of research in water resources and supply to determine the potential for using radioisotope technology in this research. Problem areas in the application of tracers in this research are being investigated through the evaluation of past experimentation with radioisotopic techniques and through discussions with those who are active in this work. A series of suggestions relating to these techniques will de drawn up to indicate which techniques should be developed further in order that more extensive applications may be found for them.

The objective of the study which is being carried out under contract AT(30-1)-2477 is the exploration of all aspects of research in water resources and supply to determine the potential for using radioisotope technology in this research. Problem areas in the application of tracers in this research are being investigated through the evaluation of past experimentation with radioisotopic techniques and through discussions with those who are active in this work. A series of suggestions relating to these techniques will de drawn up to indicate which techniques should be developed further in order that more extensive applications may be found for them.

A program has begun embodying a study of the diffusion rates of krypton and xenon into unirradiated UO2 and UC at temperatures between 1000°C and 2500°C.The experimental technique is described in some detail, involving exposure of UO2 and UC samples to a Kr85 atmosphere at various temperatures, removal of surface-adsorbed krypton, dissolution of the sample, collection and ion chamber measurement of the diffused Kr, and calculation of diffusion coefficients from these data.

...Development during this quarter have caused a shift in emphasis of the Pebble Bed Reactor Fuel Element Development Program from coatings on the sphere surface to coatings on individual fuel particles as the major deterrent to fission product leakage. In a high level irradiation test, cracks developed in the coatings of specimens coated with pyrolytic carbon and siliconized silicon carbide. In another high level irradiation test, a graphite sphere fueled with Al2O3 coated with UO2 particles is showing excellent fission product retention. The leakage factors (i.e. rate of release/rate of production) for long lived volatile fission products such as Kr85m, Kr87, Kr88, Xe133, Xe135 are ranging from 10 to the negative 9th to 10 to the negative 6th. If this degree of fission product retention is maintained in a large power reactor, it would result in essentially a "clean" primary loop.

Work on the preparation of graphite spheres containing thorium oxide for use as breeder elements in the Pebble Bed Reactor-Steam Power Plant is described. Graphite spheres of varying density were infiltrated with thorium nitrate solutions, followed by denitration to thorium oxide.

The coolant stream of all nuclear reactors caries some activity due to one or more of the following: a) neutron activation of coolant atoms, b) neutron activation of corrosion products carried by the coolant stream, c) fission recoil into the coolant stream, d) fission products leaking into the coolant stream. The Pebble Bed Reactor is not concerned with (1) and (b) since the helium working fluid, or coolant, has an activation cross-section which is essentially zero and its inert chemical nature effectively eliminates corrosion as a consideration. We are not concerned with (c) since developments to date, of fuel and particle coatings to reduce fission product leakage, will also prevent fission recoil into the coolant stream.

Tests were conducted to determine the friction factor of randomly packed beds of 3/4-inch diameter spheres in 8-inch and 15-1/4-inch diameter beds, and of 1-1/2-inch diameter spheres in 15-1/4-inch diameter bed. The bed depths were varied in an attempt to isolate the effects of entrance and exit losses. The bed Reynolds number, base on sphere diameter, was varied from 5,000 to 50,000.

A nuclear model has been developed for homogeneous, two-region reactors possessing a relatively large percentage of epithermal absorption in both the core and blanket region. A number of new IBM 650 programs have been developed and existing programs modified to form a group of programs, compatible with the nuclear model and with each other, which can be used for preliminary evaluation of the effed of design variable on reactor characteristics.

When light propagates with the wave normal in the direction of an optic axis of a biaxial crystal, the usual ray theory breaks down. This phenomenon can be analyzed by means of an asymptotic solution of Maxwell's equations. The intensity is governed by a partial differential equation within the phase surfaces, instead of ordinary differential equations along rays. This example slows that light does not always propagate along rays. A similar phenomenon occurs in hydromagnetics.

The spectrum of the mono-energetic neutron transport operator for a homogeneous sphere where the neutrons are scattered with spherical symmetry in the laboratory system is considered.

An approximate Boltzmann equation, known as the single relaxation model is studied here. This equation is linearized and the fundamental solution is considered. Following N. Grad, the solution, asymptotic in small values of the ratio of mean-free-path to distance from the origin, is sought. It can be shown that the fundamental solution itself gives the asymptotic description of the flow field past an object. This solution gives the asymptotic description when the distance from the origin is much greater than either the mean-free-path or the body size. This is true independently of the Knudsen number.

"We want to point out that there is a possible method for determining the anomalous magnetic moment of the Λ from the observation of metastable states of hyperframents. There are two possible sources for the apparent difference of binding energies of a hyperfragment. One of these comes from the difference of Q values due to the decay into an excited and ground states of the residual nucleus. The other possibility will arise if there exists a metastable state of the decaying hyperfragment."

Absolute (p,n) cross sections have been measured for Ti47, V51, Cr52, Co59, and Cu63 at energies between 4 and 6.5 Mov. These data plus earlier measurements of the cross section for inelastic proton scattering have been used to estimate total proton absorption cross sections for V51 and Co59. An optical model calculation using parameters giving a good fit to elastic scattering measurements predicts an absorption cross section in good agreement with the measurements for Co59. For V51, some sets of parameters gave good agreement with the measured absorption cross section, but the fit to the elastic scattering data was only fair.

"A number of mixtures of polymers and multi-unsaturated monomers have been prepared and irradiated. The content of insoluble gel of irradiated samples of these polymer-monomer mixtures has been determined by extraction."

"Additional mixtures of polymers and multi-unsaturated monomers have been prepared, irradiated and the gel content determined. The gel content determination of crosslinked polyolefins has been investigated in detail. The multi-unsaturated monomers used and radiation conditions applied up to this time have not given significant gel contents for polypropylene. the polypropylene resin used has been characterized by differential extraction."

"A new phenomenon which can, under certain circumstances, account for anomalous magnetic and spectral behavior of planar nickel(II) complexes has been discovered. This is a molecular association of the solute molecules in solvents of low coordinating power. It is shown that the magnetic moment and spectrum of bis(2.6-dimethyl1-3,5-heptanediono)nickel(II), Ni(DIBM)z, dissolved in toluene, are dependent upon both temperature and concentration.

"The visible absorption spectra of VA3, CrA3, MnA3, FeA3 and CoA3 (A=C5H7O2, the acetylacetonate anion) are reported. The interpretation of the data in respect to the symmetry and strength of the ligand fields is discussed, with special attention to the presence and magnitudes of trigonal components in ligand fields and its consistency with certain results of paramagnetic trigonal fields of appreciable magnitude are present."

"This is the first quarterly report on Task II of the subject Utilization of Radioactive Isotopes in Coal Process Research. There were two separate projects on Tank I; I. methods Development for Tritium Labeling of Coal Product Hydro-carbons, and II. Applications of Radio-Tracer Techniques to the Study of Fluidized Particle Mechanics. The following extended work on Task II concerns only Methods Development of Radio-Tracing With Tritium."

"With careful attention to details, tritium assays of satisfactory accuracy have been achieved on low activity standard samples by dry combustion and liquid scintillations counting of the product water.This method is faster, more accurate and dependable than the zinc fusion-ion chamber method fro low level tritium assays. At 380 degrees C, tritium loses from hydrocarbon tracers by isotopic exchange is significant and must be corrected for in tracer measurements at this elevated temperature."

"This is the second quarterly report under Contract AT(30-1)-2528 for the decontamination and recovery of precious metals from contaminated scrap. the emphasis on the analytical chemical techniques and methods was continued during this report period."

"The lifetimes of approximately 6 million positive mesons have been measured using a crystal controlled oscillator as a clock. The resulting decay curve was analyzed on the IBM 650 digital computer and gave a mean life of 2,211 plus or minus 0.003 µsec. The mean life of negative mu mesons in carbon was also measured and found to be 2,043 plus or minus 0.003 µsec. The resulting nuclear capture rate is (0.373 plus or minus 0.011)x10 to the 5th/sec, assuming that the decay rate of a negative mu meson bound in carbon is equal to the decay rate of the positive meson."